RPM limited motor control for TECS

I’ve been planning to make the switch to lithium ion power to achieve better range but there is one huge issue. Lithium polymer is 4.2v - 3.7v while Lithium ion is 4.2v - 2.5v so to achieve the same end of flight voltage as Lipo, you need more Li-ion cells. To get 3s Lipo performance, you need 4s Li-ion. This larger initial voltage means that motor rpm/throttle at the beginning of the flight needs to be limited to prevent burning the motor.

Essentially, what you need is a rpm sensor on the motor and a re-mapping of the throttle output of TECS to a requested rpm and some type of RPM governor that actually controls the ESC. This re-mapping needs to be active in all flight modes, including manual. One side benefit of this is that it would normalize the performance of the aircraft reguardless of the battery SOC which I suspect would make TECS perform better.

I’ve just contacted the developer for BLHeli to see if he can implement a new mode in his ESC firmware to achieve the same thing. Doing it inside the ESC is probably the better solution as it could then (potentially) be used on multirotors as well.

BLHeli says that his “closed loop” mode should do what I want but as far as I can tell, it does not.

Since there are no replies, I’m guessing I’m on my own here.

It occurred to me that maybe I could test my ideas using a Jeti Mezon in heli gov mode as it allows you to set a minimum and maximum rpm and then your throttle signal simply tells the esc where inside that range you want it to operate. I know that the Mezon governor code doesn’t work very well and is worse when you set a wide rpm range but maybe it will work well enough to allow some fixed wing testing.